System for sensing level change in vehicles

ABSTRACT

A system for sensing relative position between chassis ( 5   a,    5   b ) and axle ( 3 ) on a vehicle, which vehicle is provided with a so-called V-rod ( 1 ) mounted between the chassis ( 5   a,    5   b ) and the axle ( 3 ) where the pointed end of the V is connected by a ball joint ( 2 ) to the axle ( 3 ) of the vehicle and the opposite ends ( 1   a,    1   b ) of the V-rod ( 1 ) are connected to the chassis ( 5   a,    5   b ) of the vehicle, which ball joint ( 2 ) comprises a partly ball-shaped body ( 8 ) permanently fixed to the axle or the v-rod, encircled by a complementarily shaped collar ( 9 ) arranged round the whole or parts of the ball-shaped body ( 8 ) which ball joint ( 2 ) is covered by a cap or housing. The system is characterised in that on the ball ( 8 ) or in connection with the housing in the ball joint there are mounted a sensor ( 6 ) and an identification area ( 7 ) which is detected by the sensor ( 6 ) respectively, which identification area ( 7 ) is provided with information for registering position in at least one direction and that the sensor ( 6 ) registers the position of the identification area ( 7 ) in at least one direction.

The present invention relates to a system with a level sensor for use invehicles with air suspension or hydraulic suspension for identifying theposition of an axle in relation to the vehicle's chassis structure.

In vehicles with air suspension a device is required for detecting theposition of one or more axles in relation to the vehicle's chassis. Whenthe vehicle is loaded the device will detect this and implement acompensation of the pressure in relevant parts of the air suspensionsystem (preferably one or more air bellows) in order to keep the leveland the relative position between the axle and the chassis constant orwithin desired tolerances. In different embodiments one or more devicesmay be employed for detecting relative position between axle andchassis, depending on whether it is only level that requires to becompensated or also heeling resulting from unbalanced loading. In thiscase, if there are several axles, two or more sensors will be able tocontrol different parts of the air suspension system, for example thepressure in different air bellows. If a sensor is mounted on each sideof the vehicle, the system will be able to detect and compensate bothlevel in general and heeling to one specific side. If a heelinginhibitor is employed, it will also be possible to use only one sensorprovided the opposite side is kept at approximately the same level bymeans of the heeling inhibitor.

In a system of this kind it is normal practice to employ torsionpotentiometers as transmitters/sensors, which are influenced by rods orother mechanical connections and which furthermore communicate with anelectronic control system or a valve.

A number of systems are known in the art for relative position detectionand level/heel adjustment of this kind. From U.S. Pat. No. 6,412,790 amethod for such level identification is known where a rod is installedbetween axle and chassis, which rod operates a valve in the airsuspension circuit when the relative position changes, thus making itdesirable to adjust the level. This may be a relative distance which isboth too large and too small, depending on the loading on the vehicle.The valve then adjusts the pressure in the air bellows/spring bellows.During this process the sensor and the mechanical arrangement areexposed to fairly severe environmental stresses from stone spatter andwater in addition to the risk that loose obstacles on the road or underthe vehicle (such as chains, etc.) may damage the components or changethe geometry between chassis and axle, resulting in incorrectsensing/adjustment. A further drawback is that two sensors are requiredfor detecting and adjusting heeling. The sensors and the rod arrangementare expensive and installation must be carried out on the vehiclefactory's main assembly line to ensure that it is located in the correctposition between chassis and axle. The rod arrangement, moreover, has tobe correctly aligned on each vehicle in order to adjust the heightcorrectly.

Furthermore, from EP 1 199 196 the use is known of level identificationwithin the actual suspension bellows with, for example, an ultrasoundmeasuring device for distance measurement. The disadvantage of thissystem is that the sensor is located inside the bellows, which isinconvenient with regard to access during replacement, etc. Moreover, itis necessary to place a sensor in each bellows in order to correct theheight level accurately.

The object of the present invention is to provide an improved system forlevel identification for adjustment, and possibly also foridentification of heeling and adjustment in vehicles with air suspensionor hydraulic suspension. The system is improved with regard to thedisadvantages associated with previously known solutions and can detectheeling and level change with only one sensor.

According to the present invention a new system is provided foridentifying level change and heeling based on a so-called V-rod. FromNorwegian patent 308963 inter alia, this is known as a connectionbetween an axle and the chassis of a vehicle. The V-rod is arrangedlocated in the longitudinal direction of the vehicle and is mounted inthe bottom of the V on the axle. The mounting of the V-rod on the axleis rotatable substantially about two axes (in and across the vehicle'slongitudinal direction) and is a ball bearing. Each of the sides of theV is also connected with the chassis. Thus, when the axle moves relativeto the chassis, the angle of the V-rod relative to the chassis willchange. This applies both to level change and heeling. Thus, at a pointwhere the V-rod is connected to the axle, it will be possible to detectboth level change and heeling.

The ball bearing of the V-rod is preferably provided with an external“housing” or cap that surrounds the upper parts of the ball bearing andprotects it. This cap can be easily removed for inspection andmaintenance. According to the present invention the sensor foridentifying level and heeling is mounted inside the housing or under thecap in connection with the actual ball bearing. The sensor is thereforeprotected against external influences.

According to a preferred embodiment of the present invention, the sensoris also contact-free, there being no mechanical connection between theV-rod and a fixed point on the axle (the ball connection) which providesa representation of the relative position between chassis and axle. Thisis preferred since calibration and adjustment of the connection arethereby avoided, there are fewer parts that might break down and requireinspection and less need for individual adjustment during installation.In additional embodiments, however, it may be possible to use variousmechanical connections such as arms or the like between the sensor and arelative sensing point.

According to the present invention, therefore, a system has beenprovided for sensing the relative position between chassis and axle onthe vehicle, which vehicle is provided with a so-called V-rod mountedbetween the chassis and the axle where the pointed end of the V isconnected by a ball joint to the axle of the vehicle and the oppositeends of the V-rod are connected to the chassis of the vehicle, whichball joint comprises a partly ball-shaped body permanently fixed to theaxle or the V-rod, encircled by a complementarily shaped collar arrangedround the whole or parts of the ball-shaped body, which ball joint iscovered by a cap or housing. The invention is characterised in that onthe ball or in connection with the housing in the ball joint there aremounted a sensor and an identification area which is detected by thesensor respectively, which identification area is provided withinformation for registering position in at least one direction and thatthe sensor registers the position of the identification area in at leastone direction. Thus the sensor and the identification area areintegrated in the V-rod and can be further connected with the vehicle'scontrol of air suspension or hydraulic suspension for compensation oflevel and/or heeling.

In an embodiment, therefore, the sensor is mounted in the cap or inanother fashion in connection with the ball joint's housing while theidentification area is mounted on the ball. In a further embodiment theidentification area is mounted in the cap or in another fashion inconnection with the ball joint's housing while the sensor is mounted onthe ball.

Furthermore, the system is dependent on whether the ball in the balljoint is a part of the axle or the V-rod as long as the sensor isconnected with the cap or the housing round the ball bearing and theidentification area is provided on the ball. In alternative embodimentsthe reverse may, of course, also be the case.

In an embodiment the identification area that is detected by the sensoris provided with information for registering different positions in twodirections and the sensor registers the position of the identificationarea in these two directions. The sensor may be of several differenttypes which detect the identification area in the following manner:mechanical identification, distance identification with light, distanceidentification based on surface state as light reflection, magneticidentification or ultrasound.

The identification area is adapted to the sensor and is provided withinformation consisting of a number of individual, dissimilar sectionswith different characteristics such as: reflecting power, materialthickness, surface state or mechanical profile. For example, differentdegrees of surface roughness may be used. Magnetic sensing of anidentification area with variable thickness may, for example, also beemployed. These are solutions that for the most part are available to aperson skilled in the art.

In a further embodiment the identification area that is detected by thesensor is provided with information for registering the position in twodirections where the information in one of the directions providesprogressive position sensing while the information in the otherdirection provides sensing of the extreme points and that the sensorprogressively registers the position of the identification area in oneof the two directions in addition to which the sensor registers extremepoints in the second of the two directions. Thus progressive detectionof position in one direction can be combined with detection of extremepoints in a second direction by detection of high or low value.

Alternatively, the identification area that is detected by the sensor isprovided with information for registering position in two directions,where the information in both directions provides progressive sensing sothat the sensor progressively registers the different positions of theidentification area in one or both of the two directions.

If extreme points are detected on the identification area in onedirection, it may result in the sensor not “seeing” the identificationarea in the other direction, unless the outer limit sensing also permitsprogressive sensing in the other direction. In this case theidentification area and the sensor must be returned to a position wherethe sensor again “sees” the identification area. This is preferablyaccomplished by means of a correcting movement as the result of theouter limit signal. This correction may bring the sensor into asituation in the middle of the identification area.

In different embodiments the information in the identification area iscomposed of a majority of individual sections for progressive detectionof the position and a minority of individual sections for registeringthe extreme points.

The sensor may be connected with the identification area via amechanical connection. In this case the sensor is usually a torsionpotentiometer.

In a further embodiment the signal representing the detected position istransmitted in one or two directions from the sensor to a processingunit. If the time interval between position changes is short (i.e. rapidchanges), an alarm signal is activated for play in the ball bearing.

In yet another embodiment the signal representing the detected positionis transmitted in the direction representing heeling from the sensor toa processing unit where accumulated heeling in relation to a neutralstarting point is registered, and which processing unit activates analarm signal for dangerous heeling when the accumulated distancerepresenting heeling exceeds a predetermined value.

Various aspects of the invention are further illustrated in the attachedfigures, in which:

FIG. 1 illustrates the position of a V-rod in a vehicle;

FIG. 2 illustrates a sensor element in the mounting of the V-rod;

FIG. 3 is a schematic illustration of an embodiment of an identificationarea and sensor elements;

FIG. 4 illustrates an embodiment of an identification area.

FIG. 1 illustrates a ball joint connection 2 between V-rod and chassiswith sensor 6 in the cap over the ball 8. The partly ball-shaped body 8is encircled by the collar 9 which in turn is connected with the housing(and the cap) in such a manner that the collar 9 moves relative to theball body 8. Moreover, on the ball joint 2 on the ball 8 there isprovided an identification area 7.

Furthermore, in FIG. 2 there is illustrated a general perspective viewof an example of a V-rod 1 with rod parts 1 a, 1 b which are connectedwith respective parts of the chassis 5 a, 5 b. The axle 3 with wheel 4is further connected with the V-rod 1 via the ball joint 2.

In FIG. 3, moreover, there is illustrated an example of mechanicalconnection in an embodiment of the invention viewed from above down intothe ball joint. The identification surface 7 is provided with chambersor raised parts 10, which when moved move wheel 11 connected withtorsion potentiometers 12 which are sensors in the system.

A further embodiment is illustrated in FIG. 4 where an identificationarea is viewed from above (from the sensor). The area 7 c providesprogressive sensing of position change with several sections withdifferent characteristics while sections 7 a and 7 b provide onlysensing of whether the movement has reached an extreme point.

1. A system for sensing relative position between a chassis and an axleon a vehicle, which vehicle is provided with a V-rod mounted between thechassis and the axle where a pointed end of the V is connected by a balljoint to the axle of the vehicle and opposite ends of the V-rod areconnected to the chassis of the vehicle, which ball joint comprises apartly ball-shaped body permanently fixed to the axle or the V-rod,encircled by a complementarily shaped collar arranged round the whole orparts of the ball-shaped body, which ball joint is covered by a cap orhousing, wherein on the ball or in connection with the housing in theball joint there are mounted a sensor and an identification area whichis detected by the sensor respectively, which identification area isprovided with information for registering position in at least onedirection and that the sensor registers the position of theidentification area in at least one direction.
 2. A system according toclaim 1, wherein the identification area which is detected by the sensoris provided with information for registering position in two directionsand the sensor registers the position of the identification area in thetwo directions.
 3. A system according to claim 1 or 2, wherein thesensor is of a type that detects the identification area in one of thefollowing ways: mechanical identification, distance identification withlight, distance identification based on surface state as lightreflection, magnetic identification or ultrasound.
 4. A system accordingto claim 1 or 2, wherein the identification area is provided withinformation consisting of a number of individual, dissimilar sectionswith different characteristics such as: reflecting power, materialthickness, surface state or mechanical profile.
 5. A system according toclaim 1 or 2, wherein the identification area which is detected by thesensor is provided with information for registering position in twodirections where the information in one of the directions providesprogressive sensing while the information in the other directionprovides sensing of the extreme points and the sensor progressivelyregisters the position of the identification area in one of the twodirections, in addition to which the sensor registers extreme points inthe second of the two directions.
 6. A system according to claim 1 or 2,wherein the identification area which is detected by a sensor isprovided with information for registering the position in two directionswhere the information in both directions provides progressive sensing sothat the sensor(s) progressively registers the position of theidentification area in one or both of the two directions.
 7. A systemaccording to claim 1 or 2, wherein the information in the identificationarea is provided with a majority of individual sections for progressivedetection of the position and a minority of individual sections forregistering position at the extreme points.
 8. A system according toclaim 3, wherein the sensor is connected to the identification via amechanical connection.
 9. A system according to claim 8, wherein thesensor is a torsion potentiometer.
 10. A system according to claim 1,wherein a signal representing the detected position in one or twodirections is transmitted from the sensor to a processing unit, which inthe event of rapid changes of position activates an alarm signal forplay in the ball bearing.
 11. A system according to claim 1, wherein asignal representing the detected distance in the direction representingheeling is transmitted from the sensor to a processing unit whereaccumulated heeling relative to a neutral starting point is registered,and which processing unit activates an alarm signal for dangerousheeling when the accumulated distance representing heeling exceeds apredetermined value.